Benign and Malignant Thyroid Disease Among Those Exposed as Children to Fallout from the Chornobyl AccidentThe Chernobyl nuclear reactor accident in Ukraine in 1986 contaminated large parts of Belarus, northwestern Ukraine, and bordering Russian provinces. A case-control study in Belarus, with individual dose estimates, demonstrated a statistically significant link between thyroid cancer and radiation dose from fallout related to the Chornobyl accident. With the assistance of the Department of Energy (DOE) and the Nuclear Regulatory Commission (NRC), NCI has organized long-term follow-up studies of benign and malignant thyroid disease among those exposed as children to fallout from the Chornobyl accident in Belarus and in Ukraine. To date, the thyroid glands of approximately 12,000 subjects in each country have been screened biennially. A prevalence analysis of thyroid cancer based on data from the first screening in Ukraine has been published in JNCI. A paper on autoimmune thyroiditis has been accepted by JCEM.Cancer Mortality Among the Population Exposed to Radioactive Waste Dumped in the Techa River Adjacent to the Mayak Nuclear Facility in RussiaVillagers living along the banks of the Techa River in Russia were exposed to chronic external and internal radiation from the Mayak nuclear facility. Cancer mortality is being evaluated in a cohort of approximately 30,000 people who received large doses of radiation from the radioactive waste dumped into the river. Current efforts focus on improving data quality, tracing the population for vital status information, and on statistical analyses. Ans association between cancer mortality and radiation dose has been observed. Thyroid Nodules as a Measure of Radiation Risk Among a Population of 3000 Residents in Kazakhstan Exposed as Children to Fallout from Nuclear Testing at the Semipalatinsk Test Site: Thyroid nodule prevalence, determined by ultrasound screening, was used as the main outcome variable for evaluating the effects of fallout exposure in a population of 3000 village residents in Kazakhstan affected by radioactive fallout from nuclear bomb tests at the nearby Semipalatinsk Test Site during 1949-1962. Ninety-four percent of subjects were under 18 years of age in 1949 or were born during the period of testing. One or more prevalent nodules, 3 mm or more in diameter, were detected in 31% of all subjects (18% of males and 39% of females). A new dose-reconstruction algorithm, developed jointly by NCI and the Institute of Biophysics in Moscow, was used to estimate individual thyroid doses from external and internal sources of fallout-derived radiation, based mainly upon residential history and estimated consumption of milk from dairy animals grazing on contaminated pasture. Both external and internal dose were found to be significantly and independently associated with nodule prevalence after adjustment for sex and for age at screening. Current efforts, which include obtaining new information through the use of focus group interviews and application of statistical methods that take account of random errors in estimated dose, are focused on sources of uncertainty, especially those involving internal dose from radioactive isotopes of iodine ingested through the pasture-to-milk food chain.Lung Cancer and High Levels of Indoor Radon in ChinaIn collaboration with the Biostatistics Branch, tobacco data from a comprehensive case-control study of lung cancer in rural China in which high levels of indoor radon increased lung cancer risk was pooled with data from other large case-control study of lung cancer and tobacco, in order to evaluate effect modification of risk by smoking intensity.Ultraviolet Sunlight Exposure, Ionizing Radiation, and Risk of Skin and Other CancersExposure to ultraviolet (UV) radiation from sunlight plays a predominant role in the etiology of melanoma and non-melanoma skin cancer.